Ground clamp



May 20, 1947.

H. H. MERRIMAN GROUND CLAMP iliiii I I I: i l I 1 l I 8W? e m i I 28 F/g A F/g Z7- H'EN YHME RIAMN Patented May 20, 1947 UNITED STATES GROUND CLAMP Henry H. Merriman, Jackson, Mich, assignor to Harry .D. Boardman,

trustee Jackson, Mich, as

Application November 7;, 1942, Serial No. 464,903

3 Claims.

The present invention relates to welding clamps and more particularly to C clamps adapted to be clamped to some part of work to be arc welded for the purpose of making a ground connection.

lamps of the type to which the present invention relates have been heretofore known, but have not been wholly satisfactory due to the fact that it was not possible to make a good ground connection and the clamps were not flexible enough in operation to meet all of the requirements arising in use. The clamp according to the present invention fulfills the requirements for an efficient welding ground in that it provides an efficient ground connection and is adaptable to a variety of uses. Furthermore in special cases it may be used as a ground connection by merely laying the same against the member to which it is to be grounded without endangering or in any way harming the operative portion of the clamp.

An object of the invention is to provide a ground clamp having a substantial area of contact with the member to which it is attached.

Another object of the invention is to provide a ground clamp of the character described having a serrated contact surface.

Still another object of the invention is to provide a ground clamp having a contacting lug which is insulated from the clamp body.

A further object of the invention is to provide a ground clamp of the character described provided with a contacting lug which is attachable to the clamp body in a plurality of relationships.

A still further object of the invention is to provide a ground clamp of the character described having a contacting lug provided with an attaching tab which has clearance from the member to which the clamp is secured. 1

These and other objects residing in the arrangement, combination and construction of the parts will be apparent from the following specification when taken with the accompanying drawings, in which l is a side elevation of one embodiment of the invention,

Fig. 2 is a section on the line II-II of Fig. 1,

Fig. 3 is a plan view of the contacting lug of the clamp disclosed in Figs. 1 and 2, and

Fig. 4 discloses the invention associated with a different form of clamp to that disclosed in Fig. 1.

Re erring particularly to the drawings, the reference character I indicates a C clamp body of a conventional construction although it will be understood that any particular type of clamping frames desired may be employed. The frame is provided with anadjustable clamping bar 2 having a handle 3 and a combination quick feeding slip structure l associated with the clamping screw 5. The structure 4 may be of any desired design, but preferably corresponds to that disclosed in the co-pending application of Ralph N. Richards, Serial No. 377,409, filed February 5, 1941, issued as Patent No. 2,313,361 on March 9, 1943. Disclosed at the working end of the bar 2 is a foot 6 having a conventional ball and socket connection I with the bar 2 for permitting a limited rocking movement of the foot 6. The foot 6 constitutes one clamping face of the clamp. The second clamping face is constituted by a contact lug 8. The contact lug 8 is secured to re clamp body I, on a suitable lug supporting portion, by a screw 9 passing through a bore ID in the clamp body I and having a threaded engagement with the contact lug 8. The contact lug 8 is provided with a shoulder I5 which as shown in the drawings is complementary to. an upstanding shoulder IE on the clamp body I adjacent to the lug supporting portion. The shoulder I5 serves as a driving shoulder so that when the clamp is secured to a member I! for example, and oscillated about an axis parallel to the axis of the bar 2, the shoulder I6 drives the contact lug 8 causing the same to oscillate also.

The contacting surface I8 of the contact lug 8 is provided with a plurality of grooves I9 in the surface thereof for the purpose of facilitating the cleaning of the member I'I when the clamp is secured thereto. The clamp is secured to the member H by axially moving bar 2 and with it the foot 6 until the foot 6 bears a ainst the memher Ill. The member I! is urged then against the contact face I8 of contact log 8 and the handle 3 is rotated to clamp the member I! between the foot 6 and the contact surface I8. An oscillating of the clamp about an axis parallel to the axis of the bar 2 will cause the edges of the grooves l9 to scrape the surface of the member IT. This scraping will cause paint, dirt, dust particles and the like to be removed from the surface of the member H and they will drop into the grooves I9 thereby providing a good clean ground connection between the member ll and the contact lug 8.

The screw is insulated from the clamp body I by an insulating bushing 20 and an insulating washer H. The contact lug 8 is insulated from the body I by an insulating plate 22 placed between the bottom of the lug 8 and the clamp body 'I and an insulating plate 23 placed between the shoulder it of the clamp body I and the shoulder [5 of the lug B. The insulating plate 22 is retained in its position by the screw 9 and the insulating plate 23 is retained in position by insulating pins 24 extending through the insulating plate 23 and into the clamp body I as shown particularly in dotted outline in Fig. l.

The contact lug 8 is provided with a ground wire connecting tab 28 having a bore 29 therein for the purpose of receiving a suitable clamping bolt not shown. The tab 28 is arranged so that the upper surface 30 thereof is spaced downwardly from the contact surface l8 of the lug.

so that the head of a connecting bolt 3! shown in dotted outline in Fig. 1 will clear the member H.

The lug 8 is so positioned as shown in Fig. 1 with respect to the clamp body I that the tab extends to the right as shown in Fig. 1. One feature of the invention is that the lug 8 is so shaped that the tab 28 may extend either forwardly or rearwardly or to the side of the clamp body l with respect to its position as shown in Fig. 1'. provided with shoulders 32 and 33 which are spaced. the same distance from the threaded bolt receiving opening 34 as the shoulder 15 so that any one of the shoulders 15, 32 or 33 may be arranged in complementary relation to the shoulder iii of the clamp body to enabl the shoulder I 6 to act as a driving shoulder when the clamp body I is oscillated about an axis parallel to the axis of the bar 2 as hereinabove described. While the lug 8 as shown in the drawings is square to achieve the results specified, it will be understood that the same result may be achieved by shapes other than square so long as the spacing between the shoulders and the opening 36 remains the same.

With this construction, the polygonal or substantially square contact lug 8 having the ground wire connecting tab 28' extending substantially laterally or radially therefrom can be mounted in the recessed or cut away lug supporting portion of the clamp body for positioning of the connecting tab to extend laterally or radially in any one of three different positions, substantially 90 apart. In each position, the upstanding shoulder 16 on the clamp body serves to retain the contact lug 8 with the connectingtab 28 extending r projecting in the desired direc tion, and against swinging or shifting movement. The insulating plate 23, being interposed between the shoulder or face l of the lug S and the upstanding shoulder N5 of the clamp body I assures proper insulation of contact lug- 8 when in each of its settings.

The form of the invention disclosed in Fig. 4

To achieve these results, the lug 8 is is the same as that disclosed in Figs. 1, 2 and 3 not applicable to any one particular type of clamp.

Having thus described my invention, what I desire to secure by Letters Patent and claim is:

1. A Welding clamp comprising a clamp body having clamping means at one end and a bore at the other end with a shoulder upstanding adjacent to the bore, a polygonal contact lug with which the clamping means cooperates to clamp and electrically connect a member to be welded, said lug having a registering bore opening and being provided With a laterally extending connecting tab, and means received in the bores mounting the contact lug on the clamp body with a selected side thereof in juxtaposition to the shoulder.

2. A welding clamp comprising a substantially C-shaped clamp body having a contact lug supporting portion at one end with an upstanding shoulder adjacent thereto, an adjustable clamping bar at the other end of the body, a contact lug having a plurality of faces and provided with a laterally extending Wire connecting tab, and means adjustably securing said lug on the supporting portion of the body with a selected face of the lug adjacent and complementary to the first-named shoulder.

3. A welding clamp comprising a substantially G-shaped clamp body having a contact lug receiving portion at one end and provided with an upstanding shoulder adjacent to the contact lug receiving portion, clamping means at the other end of the body movable toward and away from the lug receiving portion, a contact lug of substantially polygonal form with a plurality of side faces and with an end face serving as a contact surface, a wire attaching tab projecting laterally from one of the side faces of said contact lug, said tab being in a plane spaced away from the plane of the contact surface of said lug, and means for mounting the contact lug on the lug receiving portion of the clamp body with the connecting tab extending in a desired direction and with a side on the contact lug in juxtaposition to the shoulder, whereby the contact lug is held against twisting movement and a wire joined to said connecting tab will be held out of the plane of the contact face of the connecting lug.

HENRY H. MERRIMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,071,959 Wayman Feb. 23, 1937 378,896 Mooney Mar. 6, 1888 2,025,363 Taylor Dec. 24, 1935 1,549,300 Douglas Aug. 11, 1925 1,675,114 Laird June 26, 1928 

